Tim Harford seems to be showing up again and again in the world of rational decision making, from newspapers (he is a columnist for the Financial Times) to podcasts (Fifty Things That Made the Modern Economy, Cautionary Tales, etc.) to radio (More or Less) to books (The Undercover Economist, How to Make the World Add Up, The Data Detective, plus several others). Reading his clear writing or listening to his illuminating illustrations of complex economic and statistical concepts makes it easy to see why he has been so well followed.
The last two books are actually the same book; How to Make the World Add Up: Ten Rules for Thinking Differently about Numbers is the worldwide title for a book called The Data Detective: Ten Easy Rules to Make Sense of Statistics in the US. Even though I am in the US, I own the book with the UK-release title, because I wanted to read it as soon as it was available and not wait for the US release. I was not disappointed. Harford’s ability to use anecdotes to spotlight mistakes we make (Cautionary Tales was his podcast that focused on the disastrous results of bad decisions) and to discuss how to improve our decision approach was a joy to read, and anyone new to the field of behavioral economics will benefit from its reading.
I don’t think I am giving away too much of the book by mentioning the ten rules, since they are also his chapter headings:
1 – Search Your Feelings
2 – Ponder Your Personal Experience
3 – Avoid Premature Enumeration
4 – Step Back and Enjoy the View
5 – Get the Back Story
6 – Ask Who Is Missing
7 – Demand Transparency When the Computer Says ‘No’
8 – Don’t Take Statistical Bedrock for Granted
9 – Remember That Misinformation Can Be Beautiful Too
10 – Keep an Open Mind
His final chapter is his “Golden Rule” – Be curious. If you are only reading to understand the “Ten Rules”, this is probably the only chapter you need to read. Some of the rules are ambiguously stated (is it clear what he means when he says to “Avoid Premature Enumeration”?), but become clearer when you read the chapter (here, that deeper insight comes with curious questions, and you need to figure out what claims “mean”). In all honesty, that clause alone is probably enough to give you the lesson from rule 3, but if you stop there, you’ll miss the elucidating story of Oxfam claiming that the top 85 billionaires are worth more than the bottom half of the population (there is a lot to unpack here, so don’t just cite this statistic without understanding what it means!).
I didn’t find anything ground-breaking or novel in this book, but I still really enjoyed it. It is a nice compilation of some of the research in behavioral biases and heuristics (think Kahneman, Tversky, Ariely, Fischoff, Beyth, etc.) with some of the newer criticisms of the conclusions (a lovely shout-out to Caroline Criado Perez’s Invisible Women about the pitfalls of only including men in everything from psychological to medical experiments). Most of all, the stories Harford weaves throughout the narrative help make the lessons stick. The research is sound, and the presentation is engaging.